Level gauge systems are widely used for determining the filling level in various types of tanks based on the time-of-flight of an electromagnetic signal to the surface of the product in the tank and back following reflection at the surface.
In recent years, there has been an increasing demand for wireless level gauge systems or level gauge systems with other limitations on energy consumption, such as for example so called loop-powered systems that may be connected by a 4-20 mA current loop. Wireless level gauge systems may, for example, be powered by batteries or solar power.
For such level gauge systems with a limited supply of energy it is advantageous to reduce the average energy consumption, as this will, for example, increase the lifetime of batteries in battery-powered systems.
A well-known way of reducing the average energy consumption of various measurement systems, including level gauge systems, is to operate the system intermittently, that is, controlling the system between an active state where measurements are performed, and an inactive state (sometimes referred to as a sleep state or a standby state) where most of the system is shut-down so that no or only very little energy is consumed.
This type of intermittent operation of a wireless level gauge system is, for example, described in US 2008/0278145. In the wireless level gauge system according to US 2008/0278145, arbitration logic ensures that active periods of the measurement unit occur when the wireless communication is inactive.
Although US 2008/0278145 provides for an energy-efficient wireless level gauge system, there appears to be room for further improvement in terms of optimizing the tradeoff between energy consumption and measurement accuracy.